Low-Intensity Femtosecond Radiation Activates the Natural Defenses of Mice in vivo.

The possibility of induction of cytogenetic damage in the bone marrow, changes in the cellularity of lymphoid organs and blood composition in mice irradiated with low-intensity femtosecond laser radiation at a power flux density of 5.1, 10.4, and 52 mJ/cm2 (0.5 mW for 5, 10, and 50 s) in vivo was shown. Using the radiation adaptive response test (0.1 Gy + 1.5 Gy), it was found that, when mice were exposed to femtosecond laser radiation in high doses, the body's natural defenses were activated in the same narrow range of energy flux density (2-16 mJ/cm2) as in the case of X-ray irradiation in a dose of 0.1 Gy (4 mJ/cm2). The data obtained suggest a similar mechanism of activation of the body's natural defense upon exposure to low doses of both ionizing and non-ionizing radiation.

Low dose of carbon ion irradiation induces early delayed cognitive impairments in mice.

People often encounter various sources of ionizing radiation, both in modern medicine and under various environmental conditions, such as space travel, nuclear power plants or in conditions of man-made disasters that may lead to long-term cognitive impairment. Whilst the effect of exposure to low and high doses of gamma and X-radiation on the central nervous system (CNS) has been well investigated, the consequences of protons and heavy ions irradiation are quite different and poorly understood. As for the assessment of long-term effects of carbon ions on cognitive abilities and neurodegeneration, very few data appeared in the literature. The main object of the research is to investigate the effects of accelerated carbon ions on the cognitive function. Experiments were performed on male SHK mice at an age of two months. Mice were irradiated with a dose of 0.7 Gy of accelerated carbon ions with an energy of 450 meV/n in spread-out Bragg peak (SOBP) on a U-70 particle accelerator (Protvino, Russia). Two months after the irradiation, mice were tested for total activity, spatial learning, as well as long- and short-term hippocampus-dependent memory. One month after the evaluation of cognitive activity, histological analysis of dorsal hippocampus was carried out to assess its morphological state and to reveal late neuronal degeneration. It was found that the mice irradiated with accelerated carbon ions develop an altered behavioral pattern characterized by anxiety and a shortage in hippocampal-dependent memory retention, but not in episodic memory. Nissl staining revealed a reduction in the number of cells in the dorsal hippocampus of irradiated mice, with the most pronounced reduction in cell density observed in the dentate gyrus (DG) hilus. Also, the length of the CA3 field of the dorsal hippocampus was significantly reduced, and the number of cells in it was moderately decreased. Experiments with the use of Fluoro-Jade B (FJB) staining revealed no FJB-positive regions in the dorsal hippocampus of irradiated and control animals 3 months after the irradiation. Thus, no morbid cells were detected in irradiated and control groups. The results obtained indicate that total irradiation with a low dose of carbon ions can produce a cognitive deficit in adult mice without evidence of neurodegenerative pathologic changes.

The Effect of Low and Medium Doses of Proton Pencil Scanning Beam on the Blood-Forming Organs during Total Irradiation of Mice.

The aim of this work was to study the effect of proton pencil beam scanning in the Bragg peak in the dose range of 0.1-1.5 Gy on the induction of cytogenetic damage in the bone marrow, reactive oxygen species (ROS) production in whole blood, and the state of lymphoid organs after total body irradiation of mice. Irradiation was carried out in the Prometeus proton synchrotron (Protvino) in the Bragg peak with proton energy at the output of 90-116 MeV. It was found that, under irradiation of mice in the range of low and medium doses of proton pencil beam scanning in the Bragg peak, the relative biological effectiveness (RBE) according to the criterion of cytogenetic changes was 1.15. In addition, it was found that the pathophysiological effect on the lymphoid organs and the production of ROS by blood cells were different as compared with the effect of X-rays.

Combined Effect of Low-Intensity Helium-Neon Laser and X-Ray Radiation on in Vivo Cellular Response of the Whole Blood and Lymphoid Organs in Mice.

We studied the effect of exposure to helium-neon laser (dose range 0.16-50 mJ/cm2) on activation of natural protection reserve in mice using the adaptive response test. DNA comets method revealed a protective response manifested in DNA damage level in whole blood leukocytes of mice and in lymphoid organs by the thymus and spleen weight index; preexposure to laser did not induce the adaptive response. ROS level in the whole blood was assessed by the level of zymosan-induced luminol chemiluminescence. In mice subjected to adaptive laser irradiation in doses of 0.16-5 mJ/cm2 followed by X-ray irradiation in a dose of 1.5 Gy, the activation index calculated as the ratio of induced to spontaneous area of luminescence was by 1.4 times lower than that in non-irradiated animals, which attested to reduced ROSgeneration reserve capacity of neutrophils.

Induction of the Adaptive Response in Mice Exposed to He-Ne Laser and X-Ray Radiation.

We studied the dose-dependent induction of in vivo adaptive response in the bone marrow and blood of mice exposed to low-intensity radiation of He-Ne laser (633 nm) and X-ray radiation by the severity of cytogenetic injury and intensity of ROS production, respectively. Induction of the adaptive response in mice preexposed to He-Ne laser and X-ray radiation depended on the adaptive dose and the interval between the adaptive and main doses and correlated with changes in ROS generation. The adaptive response after exposure to low-intensity ionizing and non-ionizing radiation was observed in the same dose range, which attests to similar mechanisms of its induction.

[Induction of DNA damage in blood leucocytes and of cytogenetic injuries in bone marrow polychromatic erythrocytes in mice exposed to low-LET and high-LET radiation and in their progeny].

The present work was aimed at studying the molecular and cellular levels of the response of the hematopoietic system in mice and their progeny to the action of low-LET and high-LET radiation at different times after exposure. The damage to the genome at the molecular level was assessed by the comet assay in peripheral blood leucocytes, whereas at the cellular level it was estimated by means of the micronuclear test in the marrow cells, after exposure of mice to X-radiation of 1, 3 and 5 Gy and to a high-LET low-intensity radiation at thedoses of 0.14 and 0.35 Gy, as well as to a combined effect of these types of radiation. When accessing the level of the DNA damage to individual cells by the comet assay, we also used, apart from a commonly accepted parameter %TDNA, additional characteristics: the proportions of leucocytes with an intact and highly fragmented DNA. Using these parameters, we detected the changes characterizing the dynamics of the leukocyte population in mouse blood at different times after the action of X-ray and high-LET radiation. It was found that: (1) the DNA damage increases with the dose of high-LET radiation; (2) the level of damage in the progeny of the animals exposed to high-LET radiation does not differ from that in unirradiated animals both at the molecular and cytogenetic levels; and (3) a decrease in the radiosensitivity of the progeny of the mice exposed to high-LET radiation at a dose of 0.35 Gy makes itself evident only at the molecular level, which may point to the possible transgeneration transmission of genomic lesions.

Effect of dopamine on Ehrlich ascites carcinoma cells.

Morphological studies showed that daily intraperitoneal injections of dopamine in doses of 10(-2)and 10(-1)M down-regulates the general number of cells in the Ehrlich ascites carcinoma in 10 and 30 times and decreases their diameter by 27% and 59%, respectively (as compared to the control animals received physiological saline). According to ultrastructural data these injections were followed by the abnormal changes in microvilluses, forming the specific moire fringes in cytosol, thickening of cortical layer, and a significant increase in filament reticulum density (actin fibers) in tumor cells of treatment group specimens. We concluded that the oncocytotoxic effect of dopamine was related to the induced polymerization of cytosol actin.

[Influence of low-dose-rate red and near-infrared radiations on the level of reactive oxygen species, the genetic apparatus and the tumor growth in mice in vivo].

The effect of low-dose-rate red and near-infrared radiations from the matrix of light emitted diode (650 nm and 850 nm) and a He-Ne laser (633 nm) on activation of the reserve of a natural defense system in the mice exposed to radiation in vivo was studied by the level of reactive oxygen species (ROS) production in blood cells, the induction of cytogenetic adaptive response in bone marrow cells, thymus and spleen, and the rate of Ehrlich ascites carcinoma growth in a solid form. As a positive control animals were irradiated with X-rays by the scheme of the radiation-induced adaptive response (0.1 Gy + 1.5 Gy). The levels of ROS production was assessed in whole blood by luminol-dependent chemiluminescence, of cytogenetic damage--by the "micronucleus test" in the bone marrow, the weight of the thymus and spleen--by index of organ, and the rate of tumor growth--according to its size for 30 days after inoculation. Adaptogenic and anticarcinogenic effects of studied radiations were revealed. The values of these effects were not different from those in animals pre-irradiated with the X-rays. The relationship between the level of ROS production and adaptive response induction in the mice under the influence of non-ionizing radiation was first ascertained. The experimental data obtained may indicate a similar mechanism of induction of protective responses to ionizing and non-ionizing radiations in mice in vivo.

Effect of infrared and X-ray radiation on thymus cells and the rate of growth of Ehrlich carcinoma.

We studied the effect of infrared light with a wavelength of 850 nm and modulated frequency of 101 Hz and X-ray radiation on the induction of cross-adaptive and radiation responses in the thymus and on the rate of tumor growth in mice in vivo. Preliminary exposure to infrared and X-ray radiation was shown to result in recovery in thymus weight after irradiation in a dose of 1.5 Gy and also inhibited the growth rate of Ehrlich carcinoma. These data attest to common mechanisms of the adaptive response induced by infrared and X-ray radiation in mice. Infrared light can be used as an adaptogen to adapt the animals to adverse factors.

Delayed effects of chronic low-dose high linear energy transfer (LET) radiation on mice in vivo.

In the present work, the delayed effects of chronic high linear energy transfer (LET) radiation in polychromatic erythrocytes (PCEs) of mice bone marrow were investigated in vivo. Irradiation of the two-month-old SHK white mongrel random-bred male mice was performed in the radiation field behind the concrete shield of the accelerator of 70 GeV protons to accumulate doses of 0.005-0.16 Gy. The dependence of the biological response on dose, adaptive response (AR) and genomic instability (GI) in F(1) and F(2) generations from males irradiated with doses of 0.005 and 0.16 Gy and from males exposed to combined action of immunomodulator-bendazol hydrochloride (BH) and of 0.16 Gy irradiation, were examined using the micronucleus formation test. The data demonstrated that irradiation of mice with these doses lead to an increase in the level of cytogenetic damage and induces no AR. With analysis of the bone marrow radiosensitivity to 1.5 Gy of X rays and the capacity to AR it was found that the chronic high-LET irradiation of parents induced the GI at least two generations. The combined exposure to BH and the dose of 0.16 Gy induces no AR in F(0) generation but induces AR in F(1) and F(2) offspring.

[The effect of infrared and X-ray radiation on the production of reactive oxygen species in blood and induction of cytogenetic damage in the bone marrow of mice in vivo].

The goal of the present work was to study the effect of infrared light (IRL) at a wavelength of 850 nm modulated by a frequency of 101 Hz with a mode of power 22 mW/cm2 and X-rays with a voltage of 200 kV at a dose rate of 1 Gy/min on the production of reactive oxygen species (ROS) in blood cells using luminol-dependent chemiluminescence, as well as on the induction of a cytogenetic damage in bone marrow cells of mice by the in vivo micronucleus test. The experiments performed have shown: 1) the level of the ROS production in blood of the mice exposed to IRL and X-rays at an adapting dose of 0.1 Gy reaches the peak value after 0.5 h and drops to the ROS level in untreated animals 5 h after either exposure; 2) irradiation of mice with IRL and X-rays at a dose of 0.1 Gy induces adaptive responses both in blood cells and bone marrow cells of mice. These adaptive responses were revealed only 5 h after both exposures, when the level of ROS production decreased to the ROS level in untreated animals; they are equal in magnitude and dynamics and persist up to 2 months.

101 Hz frequency-modulated infrared light induces cytogenetic adaptive response in mouse bone marrow in vivo.

The micronucleus test was used tu study the possibility of inducing cross-adaptive response in mouse bone marrow cells in vivo with an 850 nm infrared light modulated by a 101 Hz frequency, emitted by a light therapy device "Kurator". We demonstrated that this exposure led to a substantial reduction of cytogenetic cell damage produced by further exposure of animals to X-radiation in the dose of 1.5 Gy, i.e. it induced an adaptive response which did not differ by the magnitude and time course from the adaptive response to radiation.

[Study of the genetic instability in generations of mice irradiated of a low-dose rate of high-LET radiation].

In present work, we investigated the genetic instability in mice of F1, of F2 and of F3 generations born from males irradiated by a low-dose rate of high-LET radiation that simulates the spectral and component composition of radiation fields formed in the conditions of high-altitude flights in vivo in polychromatic erythrocytes of bone marrow using the micronucleus test. Two-month-old males of SHK white mongrel mice were used. Irradiation was performed for 24 h a day in the radiation field behind the concrete shield of the U-70 accelerator of 70 GeV protons (Serpukhov) to accumulate doses of 11.5, of 21.5 and of 31.5 cGy (1 cGy/day). The experiments demonstrated that in mice of F1 generation born from males irradiated with doses of 11.5, 21.5 and of 31.5 cGy, an increase in sensitivity to additional irradiation with a dose of 1.5 Gy of gamma-radiation and the absence of adaptive response compared with the descendants of unirradiated males occur. In contrast to F1 generation genetic instability in mice of the F2 and F3 generations was revealed only by the absence of adaptive response. These data indicate a genetic instability in F1, F2 and F3 generations born from irradiated males.

[Molecular-genetic and epidemiologic examination of personnel subjected to occupational irradiation in Russian Federal Nuclear Center (Sarov). Report 3. Genetic characteristics of adaptive norm].

Was undertaken the effort to define the limits of the adaptive norms and of high risk groups in regard to the work connected with fissile materials (FM), radioactive materials (RM) and ionizing radiation sources (IRS). In view of the aforementioned goal it was made a comparative evaluation of the individual radiosensitivity measurements and anthropometric indicators in the cohort formed from VNIIEF personnel, which was exposed to a constant occupational gamma-neutron irradiation, as well as the non-irradiated cohort. There were analyzed the dispersion dependencies on height, on chest and on head circumference and heterozygosis by 9 loci. It was found that the minimum chest circumference dispersion is observed in people with average heterozygosis equal to 3 (at the 95% credibility). The minimum head circumference and height dispersion is observed in people with average heterozygosis equal to 3-5. The largest jitter in metric indicators is characteristic for people with heterozygosis 2. The highest radiosensitivity is typical for such individuals as well. It was formulated the assumption that this category of people present the limit heterozygosis case. So, additional research looking at people with the limit heterozygosis values (2 and 7; 8) is required, in order to define individual radiosensitivity limits.

[Molecular-genetic and epidemiologic examination of personnel subjected to occupational irradiation in Russian Federal Nuclear Center (Sarov). Report 1. Genome structural damage rate and radiosensitivity].

A comparative evaluation of the cytological and dosimetric examination of the cohort comprised by VNIEF personnel subjected chronically to gamma-neutron ionizing radiation, as well as non-irradiated cohort is given. The obtained data on the influence of the occupational and on X-ray irradiation, age and smoking on the rate of structural genome damage, as well as the activity of the human repair system activity are presented. The influence of the individual heterozygosis by 9 polymorphous loci: Hp, Tf, Gc; 6-PGD, EsD, ACP, PGM1, microsatellite lici SCF1PO and F13AO1 is shown.

[Peculiar effects of low doses of high let radiation on mice].

Experiments with exposure of mice to low doses of chronic high-LET radiation were carried out in the radiation field behind the concrete wall of the Serpukhov accelerators of protons with the energy of 70 GeV. The goal was to study dose dependence, radiation adaptive response (AR), and genetic instability. Mice (SHK strain) were irradiated continuously 15, 24 and 31 days which corresponded to the doses of 11.5, 21.5 and 31.5 Gy. Cytogenetic damages were determined using the micronuclear test in marrow polychromatophil erythrocytes. It was shown that all the experimental doses aggravated the cytogenetic damage; however, no AR induction in marrow cells was observed. Males of the F1 generation born from the males irradiated at 11.5 Gy had same level of spontaneous cytogenetic damage as males born from non-irradiated parents. Yet, they displayed an exaggerated sensitivity to additional exposure to 1.5 Gy and no AR induction by the standard gamma-protocol which is indicative of genetic instability.

[The effect of low-dose rate radiation simulating the high-altitude flight conditions on mice in vivo].

In present work, we investigated the peculiarities of the effect of a low-dose rate high-LET radiation that simulates the spectral and component composition of the radiation field formed in the atmosphere at a height of 10 km on mice in vivo. The dose dependence and adaptive response were examined. Irradiation of mice was performed for 24 h a day in the radiation field behind the concrete shield of the Serpukhov accelerator of 70 GeV protons for the time (15-31 days) necessary to accumulate the required doses. The experiments demonstrated that irradiation of mice in vivo in the dose range of 11.5-31.5 cGy leads to an increase in cytogenetic damage to bone marrow cells and induces no adaptive response in bone marrow cells.

Peculiarities of the effect of low-dose-rate radiation simulating high-altitude flight conditions on mice in vivo.

In the present work, the effect of a low-dose rate of high-LET radiation in polychromatic erythrocytes of mice bone marrow was investigated in vivo. The spectral and component composition of the radiation field used was similar to that present in the atmosphere at an altitude of about 10 km. The dose dependence, adaptive response, and genetic instability in the F1 generation born from males irradiated under these conditions were examined using the micronucleus test. Irradiation of the mice was performed for 24 h per day in the radiation field behind the concrete shield of the Serpukhov accelerator. Protons of 70 GeV were used over a period of 15-31 days, to accumulate doses of 11.5-31.5 cGy. The experiment demonstrated that irradiation of mice in vivo in this dose range leads to an increase in cytogenetic damage to bone marrow cells, but does not induce any adaptive response. In mice pre-irradiated with a dose of 11.5 cGy, an increase in sensitivity was observed after an additional irradiation with a dose of 1.5 Gy. The absence of an adaptive response suggests existence of genetic instability.